Light-sensitive silver salts of thiosemicarbazones and thiocarbohydrazones

ABSTRACT

This invention comprises a novel class of light-sensitive silver compounds, and photographic systems and methods employing such compounds. These compounds are characterized by being nonsilver halides and can be represented by the formula

United States Patent [54] LIGHT-SENSITIVE SILVER SALTS OF THIOSEMICARBAZONES AND THIOCARBOHYDRAZONES 8 Claims, No Drawings [52] US. Cl.. 96/1 14.6 [5 1] Int. Cl G03c l/02,

[50] Field of Search [56] References Cited UNITED STATES PATENTS 1,560,240 1 H1925 Jelley 2,739,893 3/1956 Levy...

Primary Examiner-Norman G. Torchin Assistant Examiner-Judson R. Hightower Anomeys-W. H. J. Kline, B. D. Wiese and H. E. Byers ABSTRACT: This invention comprises a novel class of lightsensitive silver compounds, and photographic systems and methods employing such compounds. These compounds are characterized by being nonsiiver halides and can be represented by the formula 1 i S|Ag R C=NN=C-NHR,

LIGHT-SENSITIVE SILVER SALTS OF THIOSEMICARBAZONES AND THIOCARBOHYDRAZONES This invention relates to light-sensitive silver compounds, particularly to a certain light-sensitive silver compound, and to photographic systems and methods that employ such compounds.

application Ser. No. 24l,537, now U.S. Pat. No. 3,206,309, it

was found that certain nonsilver halide compounds, namely, silver mercaptides, also possess the extremely useful property of light sensitivity.

Now after further research, it has been discovered that another class of organic compounds, although in many respects chemically dissimilar to the light-sensitive mercaptides of my previous invention, also possesses the same remarkable property, namely, that light-sensitive silver compounds'and novel photographic systems employing such compounds can be prepared therefrom.

One specific object of the present invention is to provide novel photographic systemscomprising the light-sensitive silver compounds, herein described below, that can be developed by known silver halide developers and can be readily permanized after development. Other objects and ad- -vantages will appear from consideration of the following detailed description and claims.

According to the present invention photographic systems employ as a light-sensitive element a silver compound having the formula wherein R, is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals and substituted alkyl and aryl radicals;

Compounds having the above formula behave in a photographic emulsion much the same, in some respects as silver halides behave. The compounds are light sensitive, and after exposure to actinic light they will respond under certain conditions to the same developers that are used for reduction of exposed silver halides to produce a silver image. A great variety of silver halide developing solutions are described in photographic literature, and these silver halide developers are effective photographic developers for the silver compounds of this invention. The light-sensitive silver compounds of the invention are characterized by being nonsilver halide.

Stabilizing to light is obtained by using the same stabilizing agents useful for stabilizing silver halide emulsions such as, e.g., thiosulfates. thiocyanates, etc. In those instances in which a water soluble silver compound is used, washing to remove unexposed compound can be used to stabilize the element.

A convenient method for synthesis of a light-sensitive silver compound of the class described is to react the corresponding thiosemicarbazone or thiocarbohydrazone compound with an cquimolar portion of a soluble silver salt, such as silver nitrate. The reaction proceeds in aqueous solution. The optimum molar ratio of silver salt reactant to thiosemicarbazone or thiosemicarbohydrazone reactant in the reaction mixture is 1:1, and thisratio is preferred for optimum results in photographic systems.

The silver salt forreaction with the thiosemicarbazone or thiocarbohydrazone can be an inorganic, water-soluble silver salt such as silver nitrate, silver sulfate, silver acetate, silver perchlorate, and the like, or it can be an organic silver salt such as p-toluenesulfonate silver salt, and other organo silver complexes having a stability constant less than that of the resulting light-sensitive silver compound. Organic silver salts can be chosen that will release to the solution, upon reaction with the thiosemicarbazone or thiocarbohydrazone an organic ion that is useful in a photographic emulsion such as an acid, dye, hardener, etc. For example, silver p-toluenesulfonate, upon reaction with a thiosemicarbazone will release sulfonic acid which contributes necessary acid for a photographic emulsion.

Thiosemicarbazones and thiocarbohydrazone which may be utilized in the preparation of an emulsion for photographic filmand which comprise the light-sensitive silver compounds of my invention, may be represented by the formula:

wherein R, is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, and substituted alkyl and aryl radicals;

R, is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, substituted alkyl and aryl radicals, heterocyclic radicals, and polyhydroxy aldehydes; and

R, is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, substituted alkyl and aryl radicals, and

The alkyl radicals generally have one to l0 carbon atoms and can include such noninterfering substituents as alkyl, aryl, sulfonyl, carboxyl, amino, and the like. The aryl radicals are of the phenyl or naphthyl series and can include various noninterfering substituents such as alkyl, sulfonyl, carboxyl, amino and the like. Various heterocyclic radicals contemplated within the scope of this invention are preferably rings having five to six atoms such as morpholino, oxapentamethylene, pyridyl, thiazolyl, and the like. A particularly useful class of light-sensitive silver compounds used in the invention are water-soluble compounds prepared by reacting polyhydroxy aldehydes represented by the following formula:

CHr-(CH OH OH 2 wherein x is an integer one to four with thiosemicarbazide.

Typical light-sensitive silver compounds that can be utilized in the light-sensitive emulsions of the invention include:

D,L-glyceraldehyde thiosemicarbazone D-mannose thiosemicarbazone D-galactose thiosemicarbazone morpholine-Z-propanone thiosemicarbazone o-phthaldehyde monoacid thiosemicarbazone glyoxal bis(thiosemicarbazone) benzaladehyde (4-phenyl-3-thio )-semicarbazone o-tolylaldehyde thiosemicarbazone D-glucose thiosemicarbazone D-xylose thiosemicarbazone L-arabinose thiosemicarbazone propionaldehyde thiosemicarbazone p-dimethylaminobenzaldehyde thiosemicarbazone fl-morpholinoethylthio-Z-propanone thiosemicarbazone die'thylaminoQ-propanone thiosemicarbazone pyridyl-2-aldehyde(4-phenyl-3-(thio) semicarbazone benzaldehyde (4-ethyl-3-thio) semicarbazone acetone thiosemicarbazone dihydroxy acetone thiosemicarbazone benzaldehyde thiosemicarbazone nitrobenzaldehyde thiosemicarbazone oxapentamethylene-Z-propanone thiosemicarbazone thiazolyl-Z-propanone thiosemicarbazone and the like.

Also, carbohydrazones which can be used include:

L-arabinose thiocarbohydrazone D-galactose thiocarbohydrazone D-mannose thiocarbohydrazone L-rhamnose thiocarbohydrazone Double-ended thiocarbohydrazones which may be used include:

bis glucose thiocarbohydrazone bis xylose thiocarbohydrazone Synthesis of thiosemicarbazone and thiocarbohydrazone compounds used in accordance with this invention can be prepared by reaction techniques and methods well known to those skilled in the art.

An emulsion for photographic film comprises an acid solution of the light-sensitive silver compound and a film forming binder such as photographic gelatin, polyvinyl alcohol, and the like. Most conveniently a film forming binder such as gelatin is included in the same solution in which the light-sensitive silver compound is synthesized by the reaction described above, thereby making an emulsion for coating. Other conventional addenda such as sensitizers, dyes, hardeners, and the like may be included in the emulsion. The emulsion is coated on any suitable support by one of the conventional emulsion coating methods to produce a light-sensitive film on the support. Flexible supports such as paper, polymeric films, etc. are particularly useful. Of course the light-sensitive compound must be kept from light until photographic exposure.

A factor that seems necessary for light sensitivity of the emulsions containing the light-sensitive silver compound of this invention is that the emulsion preferably be acid. Emulsions having a pH number much above 4.0 do not exhibit good light-sensitivity when coated as photographic films. Optimum sensitivity for most of the light-sensitive emulsions prepared in accordance with this invention are obtained at about pH 1.5. Inorganic and organic acids may be added to the emulsion to adjust the pH value. Acids such as nitric, sulfuric, taurine, ptoluene-sulfonic acid and the like may be employed for this purpose.

The following examples are included for a further understanding of the invention:

EXAMPLE 1 A solution is prepared by dissolving 0.25 grams silver nitrate in 20 m. distilled water. To a separate beaker containing 20 ml. distilled water is added 0.34 gram 2-carboxybenzaldehyde thiosemicarbazone. The water is heated until boiling, then under suitable safelight conditions, the two water solutions are poured simultaneously into 40 ml. of 10% gelatin with agitation. Then 1.5 grams of sucrose is added. A coating is made on baryta-coated paper base at 0.006-inch wet thickness. After the coating has air dried, a strip of coating is sensitometrically exposed for 30 seconds. The exposed coating is developed for 60 seconds in a 1:1 solution of silver halide developer in water at 70 F. The development is then stopped by immersing the example for 30 seconds in 3% acetic acid, stabilized to light by immersing for 5 minutes in a fixing bath, washing and drying. The finished print has a black-toned, stepped silver image of low density. This contains practically no undeveloped silver.

The developer utilized has the following formula:

N-methyl-p-arninophenylsulfute 3.0 g.

Sodium sulfite (anhydrous) 45.0 g. Hydroquinone 12.0 g. Sodium carbonate monohydrate 80.0 g.

Potassium bromide 2.0 Water to make I liter The fixing bath has the formula:

Sodium thiolulfate (cryat.) 240.0 g. Sodium sulfite (anhydrous) I50 Acetic acid, 28% 48.0 cc. Boric acid 7.5 Potassium alum 15.0 3. Water to make 1 liter EXAMPLE 2 A. Part A consists of the following ingredients:

10 ml. distilled water 1.1 gram L-arabinose thiosemicarbazone 0.4 ml. concentrated nitric acid 0.25 ml. 40% formaldehyde 20 m1. of 10% photographic gelatin in water B. Part B consists of the following ingredients:

10 ml. distilled water 0.84 grams silver nitrate A light-sensitive coating according to this invention is prepared from the combination of Part A and Part B as follows: Part B is added to Part A with stirring, filtering, coating 0.004-inch wet thickness on a thin paper base and a thin film base.

When dry, the coatings, that is both a paper-base coating and a film-base coating, are exposed for 30 seconds, positive filter setting, on a processing control sensitometer. Processing consists of a second, 70 F. development in the developer solution of example 1, then stopping in 3% acetic acid, and washing for 30 minutes in distilled water and drying.

A neutral-toned, stepped image is obtained on both the paper and film-base coatings, the paper coating being developed considerably faster than the film base coating.

Because certain of the unexposed silver compounds of this invention, as noted previously, are water soluble they are particularly suitable for use as the light-sensitive compounds in diffusion transfer processes. Use of these soluble light-sensitive compounds instead of insoluble silver halides eliminates the need for a silver halide solvent in the diffusion transfer processing solution. Thus ordinary developing solutions can be used for such processing.

EXAMPLE 3 and while still wet with developing solution, the emulsion side is pressed for 60 seconds against a conventional diffusion transfer receiving sheet containing nickel sulfide. When the sheets are separated, a positive image appears on the receiving sheet. The experiment is repeated using other conventional diffusion transfer receiving sheets containing silver oxide and lead sulfide nuclei, and positive images are obtained.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as set forth in the appended claims.

I claim:

1. A photographic element comprising (l) a support, and (2) a water-permeable light-sensitive layer containing a lightsensitive compound having the formula wherein R is a member selected from the group consisting of hydrogen atoms, alkyl radicals, and aryl radicals; R is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, five to six atom heterocyclic radicals wherein at least one nitrogen, oxygen, or sulfur atom is a member of the heterocyclic ring, and

a OH 1 wherein x is an integer one to four; and R is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, and

said light-sensitive silver compound dispersed in a water permeable binder.

2. An emulsion useful for making light-sensitive films comprising a film-forming binder mixed in water at a pH above about four with a light-sensitive silver compound produced by reaction of about equal moles of a water-soluble silver salt and a compound having the formula:

wherein R is a member selected from the group consisting of hydrogen atoms, alkyl radicals, and aryl radicals; R is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, five to six atom heterocyclic radicals wherein at least one nitrogen, oxygen, or sulfur atom is a member of the heterocyclic ring, and

(|3H}-((|3H)" OH OH 1 wherein x is an integer one to four; and R is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, and

wherein R, is a member selected from the group consisting of hydrogen atoms, alkyl radicals, and aryl radicals; R, is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, five to six atom heterocyclic radicals wherein at least one nitrogen, oxygen, or sulfur atom is a member of the heterocyclic ring, and

a OH

wherein x is an integer one to four; and R, is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, and

a OH

and (2) developing with a silver halide developing agent.

7. A process of claim 6 in which said element while still being developed is contacted against a nucleated surface.

8. A process of claim 6 in which said element is stabilized to light after developing.

* =0 l t I mg T UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,6l5',625 DatedOCtObeI' 26, 197

Inventor(s) Grant M. Heist and Wilbert Ii Humphlett It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the specification R1 S 1 H Column 1, line 35, "R C=N-NHCNH-R should read Column 2, line 63, "morpholine" should read --morpholino---; line 75, delete parenthesis before "thio" Column 3, line 25, insert a hyphen between "film" and "forming"; line 52, "m'.'" should read --ml.

Signed and sealed this 25th day of A i 1972.

(SEAL) Attest':

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

2. An emulsion useful for making light-sensitive films comprising a film-forming binder mixed in water at a pH above about four with a light-sensitive silver compound produced by reaction of about equal moles of a water-soluble silver salt and a compound having the formula: wherein R1 is a member selected from the group consisting of hydrogen atoms, alkyl radicals, and aryl radicals; R2 is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, five to six atom heterocyclic radicals wherein at least one nitrogen, oxygen, or sulfur atom is a member of the heterocyclic ring, and wherein x is an integer one to four; and R3 is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, and
 3. A photographic element of claim 1 in which said binder is gelatin.
 4. A photographic element of claim 1 in which said support is flexible.
 5. A photographic element of claim 1 comprising a film-forming binder.
 6. A method for producing a photograph comprising (1) exposing to a pattern of actinic light an element comprising a support having thereon a light-sensitive silver compound having the formula wherein R1 is a member selected from the group consisting of hydrogen atoms, alkyl radicals, and aryl radicals; R2 is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, five to six atom heterocyclic radicals wherein at least one nitrogen, oxygen, or sulfur atom is a member of the heterocyclic ring, and wherein x is an integer one to four; and R3 is a member selected from the group consisting of hydrogen atoms, alkyl radicals, aryl radicals, and and (2) developing with a silver halide developing agent.
 7. A process of claim 6 in which said element while still being developed is contacted against a nucleated surface.
 8. A process of claim 6 in which said element is stabilized to light after developing. 